Orthogeriatric anaesthesia - studies on the bone cement implantation syndrome, risk prediction and intraoperative haemodynamics

Sammanfattning: The bone cementation implantation syndrome (BCIS), as seen in orthopaedic patients, is characterised by intraoperative hypotension and hypoxia and loss of consciousness around the time of bone cementation. In a retrospective study, the incidence of and risk factors for the BCIS and its impact on mortality during cemented hemiarthroplasty for hip fracture were evaluated. Data were retrieved by an in-depth analysis of medical records of more than 1000 patients for patient characteristics and comorbidity. A follow-up study on a population operated without cement was then reviewed and compared with patients undergoing cemented hip arthroplasty in order to isolate the effects of bone cement use on perioperative haemodynamics and mortality. For the prognostication of 30-day mortality after hip fracture surgery, we attempted an external validation and performed a recalibration of the Nottingham Hip Fracture Score (NHFS) in a large cohort of Swedish patients. Finally, we performed a prospective study on systemic haemodynamics following the use of a fractionated low-dose continuous spinal anaesthesia (CSA) in a group of 15 hip fracture patients with a high-risk score and age, using invasive haemodynamic monitoring. This neuraxial technique is not commonly used but has the potential to cause less intraoperative haemodynamic aberrations. The incidence of BCIS was 27%, with the more severe forms present in 7% of cases. Risk factors for severe BCIS were: chronic obstructive pulmonary disease, ASA grade III-IV risk, and medication with warfarin and diuretics. The incidence of hypoxia or and/or hypotension were higher in the cemented (28%) compared to the uncemented group (17%). The use of bone cement was an independent risk factor for one year mortality. External validation of the NHFS failed in its present form. Following recalibration of the formula, we could perform an internal validation in a subset of our cohort. Fractionated low-dose CSA showed a minor/moderate fall in mean arterial pressure caused by a decrease in cardiac output, in turn caused by systemic venodilation and a fall in stroke volume. In conclusion, BCIS is commonly seen in the elderly hip fracture population. Its occurrence is strongly associated to the use of bone cement and is a separate entity from anaesthesia related intraoperative hypotension. Failed external validation of the NHFS in our population implies a difficulty in applying externally developed risk prediction scores without validation. Fractionated low-dose CSA provided stable intraoperative haemodynamics. A decline in cardiac output due to reduced stroke volume was the defining trait of the minor fall in blood pressure after spinal anaesthesia.